Magnetically biased electron discharge device



June 22, 1937. D. PRINZ ET AL MAGNETICALLY BIASED ELECTRON DISCHARGEDEVICE Filed March 1 INVENTOR. DIETRICH PR|NZ FELIX HERRIGER %or FIL M HATTORNEY.

Patented June 22, 1937 UNITED STATES MAGNETICALLY BIASED ELECTRON DIS-CHARGE DEVICE Dietrich Prinz and Felix Herriger, Berlin, Germany,assignors to Telefunken Gesellschaft fur Drahtlose Telegraphic m. b.11., Berlin, Germany, a. corporation of Germany Application March 1,1935, Serial No. 8,912. In Germany March 1, 1934 9 Claims.

This invention relates to electron discharge devices, more particularlyto improvements in magnetically biased electron discharge devices inwhich the electron discharge is influenced by a magnetic field.

The conventional magnetically biased electron discharge device comprisesthree different components, that is, an electron discharge device, ameans for creating a magnetic field, and the circuit elements andvoltage sources associated with the device. The dimensions of theelectrode system of the electron discharge tube, among other things, aregoverned by the wavelength to be generated, and they must be smaller,the shorter the desired wave-length. The efficiency of device iscomparatively low when operated at ultra high frequencies, an efficiencyof about 10 per cent being considered quite favorable where waves of 50centimeters or less are dealt with. The result at these frequencies isthat thermal losses are developed in the electrode system which areseveral times greater than the useful energy which results. Inasmuch asthe electrodes for the production of ultra- 25 shortwaves must be ofvery small dimensions,

they will be capable of handling only a relatively small load and areable todeliver only a small output of oscillating energy. Hence,whenever more than the average power output is re- 30 quired, it isnecessary to connect in parallel a plurality of the magnetically biasedelectron discharge devices.

Serious difiiculty with the usual parallel connection, however, is thatthe length of the wires 35 connecting the various tubes is approximatelythe same as the length of the wave tobe generated. Hence, theseconnecting wires must be tuned to whatever wave-length is beinggenerated in order that they may not offer an unduly 4 great resistanceto the flow of radio-frequency energy and in order that during operationproper cooperation may be had between the various tubes by having aproper current and voltage phase relation between the tubes. However,the 45 necessity of such tuning makes it harder not only to adjust theparallel arrangement when operating on a given wave length, but makes itespecially difiicult to obtain a change in wavelength or frequency.There arealso a number of other difficulties which make the use of theusual parallel connections impractical. The prior practice has usuallybeen to combine two or more sets -or units each comprising an electrondischarge tube and the means for producing the 5 requisite magneticfield. When the magnetic .field is generated by the aid of anelectromagnet, the inherently high consumption of energizing energy ofthe electron discharge device when operated at ultra high frequenciesincreased many times. In the case of permanent magnets for which theweight per unit can be estimated at a little over two pounds, a parallelarrangement leads to such an increase in the weight and the volume ofthe arrangement that it can no longer be seriously considered for mostpractical cases. Another difllculty is that not only the electrical, butalso' the magnetic data of the various units have to be matched; and thenecessity of the additional adjustments means a considerable handicap inthe use of magnetically biased electron discharge tube arrangementscompared with other ways and means of generating very high frequenciessuch as the retarding-field type of circuit arrangement ofBarkhausen-Kurz.

The object of our invention is to provide an improved magnetically.biased electron discharge device which not only has a comparativelyhigh power output but is simple in construction and easy to adjust andoperate over a wide range of ultra high frequencies.

According to our invention, two, or more electron discharge devices aredisposed in the same magnetic field and operated simultaneously. For thepurpose of minimizing space requirements and reducing the air-gap to betraversed by the lines of force of the magnetic field, all electrondischarge devices are preferably accommodated inside one evacuatedenvelope. In order that the connecting leads and wires between parallelelectrode assemblies may be made as short as possible or may bedispensed with entirely, the anodes of the various electrode assembliesare structurally combined.

By the use of a joint magnetic field for all the units the use andoperation of the apparatus is substantially simplified. Theaccommodation inside a single vessel of the various electrode assembliesis conducive to a compact assembly for which the requisite magneticfield will not be substantially larger than that required for a singleelectron discharge device. If the dis charge anodes of the variousconstituent systems are directly inter-connected, the combination willbe independent of any frequency adjustment, which is necessary whereconnecting wires are used, and will thus be just as simple inmanipulation as a simple tube.

The novel features which we believe to be characteristic of ourinvention are set forth with particularity in the appended claims, butthe invention itself will best be understood by reference to thefollowing description taken in connection with the accompanying drawingin which Figure 1 is a view in elevation of a magnetically biasedelectron discharge device made according to our invention, Figure 2 is asection transverse to the longitudinal axis of a modification of a.magnetically biased electron discharge device made according to ourinvention, Figure 3 is a view partly in section of a still furthermodification of a magnetically biased electron discharge device madeaccording to our invention, Figure 4 is an enlarged longitudinal sectionof a portion of Figure 3 showing details of construction, Figure 5 showsa plurality of magnetrons such as shown in Figure 3 connected inparallel for increased output, Figure 6 is a diagrammatic showing inperspective another modification of our invention, and Figure 7 is asection transverse to the longitudinal axis of a still furthermodification of our invention.

In the modification shown in Figure 1, a permanent magnet M consistingof a material possessing a high coercive force, that is a material whichmaintains its magnetism very well, is used for providing a magneticfield. In the air-gap between the two poles P are mounted two electrondischarge devices R, each of which has a straight cathode K and a singleor multiple anode A. The circuit elements associated with the tube havebeen omitted in the drawing inasmuch as they are."

immaterial so far as the basic idea of this invention is concerned. Thetwo tubes may be operated in a push-pull circuit or in a parallelcircuit.

- In order that the magnetic field may be concenthus of each group ofanodes form roughly a trated inside the smallest possible space thetubes R are designed so that the electrode assembly comes as close aspossible to the glass wall of the envelope, so that the distance betweenthe two systems will be very small and so that the airgap between thepoles P will be small.

Both of the electrode systems could of course be accommodated within asingle evacuated envelope, in which case the electrode systems could beplaced still more closely together. The series connection of the cathodefilaments can be used inasmuch as the fall of heating voltage along thefilament can be disregarded because of the relatively high platepotential, which for very short waves may be of an order of magnitude of1000 volts. A' series connection, especially for direct supply lineoperation, offers the advantage that the excess voltage to be dissipatedin the case of direct current supply will be lower, while foralternating current supply conditions, the requirements of theheating-current transformer are more favorable.

In another modification of our invention which has proven especiallysatisfactory in combining a. plurality of magnetically biased electrondischarge devices, all of the anodes of the separate electrodeassemblies have been structurally com- I bined. In Figure 2, which is across-section transverse to a longitudinal axis, the envelope of theelectron discharge device contains six paralleled discharge paths, eachone of which includes a thermionic cathode K and a pair of anodes Al,A2. The anodes are combined into six groups to form two closed surfaceswhich are parallel to and surround the cathodes, while thecross-secplurality of joined semi-circles. It will be seen that in thisembodiment all connecting leads are dispensed with between theparalleled anode halves so that the arrangement entirely eliminates anydifiiculties which arise when the connecting leads have to be tuned asin the conventional parallel arrangements. The filaments, for example,may be connected in series so that only two connections or terminals forthe heating circuit are needed. Furthermore, only one terminal isrequired for each anode group. The six inner anode halves A2 formatubular hollow space E which may be utilized for a number of purposes.

Inasmuch as the outer anode halves Al form a I closed surface, thelatter could be used to form the wall of the envelope. This simplifiesconstruction and promotes the dissipation of heat. The mounting of thesystem as shown in Figure 2 ofiers an opportunity for a particularlyfavorable construction and formation of the power carrying connection tobe connected with the two plate groups.

In Figure 3 is shown a multiple-unit magnetically biased electrondischarge device in conjunction with concentric lines or leads which canbe used as a circuit or as transmission lines. The outer connected anodehalves Al form the lateral wall of the vacuum vessel which is closed atboth ends by insulating disk-shaped members B on which the innerelectrodes are supported. The cathode filament current lead-ins H aremounted in one of the disks B. The outer anodes Al terminate in ametallic tube E I and the inner anodes A2 (see Figure 4) terminate in ametallic tube E2. These two concentric tubes so combined provide atransmission line adapted to carry radio frequency oscillations to theuseful circuit, i. e.,

the aerial and also for conducting the direct cur-- rent supply for theanodes. The magnetic field is set up by a co-axial coil F. Ceramicmaterials have been found to be particularly suitable for the closuredisks B. These permit the use of tubular concentric lines. Vacuum tightconnections between the anodes, the filament-currnt leads and theceramic disks are provided by means of intermediate layers of glass.

Figure 4 is an enlarged longitudinal section of the modification shownin Figure 3, the illustration being schematic in nature. The two anodesystems again are denoted by Al and A2, their extensions El and E2constituting the concentric lines. The cathodes K are supported by theend disks B and can be connected in series. The electrodes are sealed inthe disk B of ceramic materials by the intermediate layers or coating ofglass Z. The inner anode group may be extended to the left in the shapeof a tube. Inside the latter is a concentric tube WI, W2. Thistube-system serves for the intake and exhaust conduits ofa coolingmedium or refrigerant which fiows along the path designated by thearrows. The coil F serves for the generation of the magnetic field.

In case a still larger power output is desired than that possible withone multi unit arrangeseveral such multi unit arrangements in parallelina very practical and satisfactory manner.

Referring to Figure 5, the outer anode systems of two multi unitarrangements TI and T2 are inter-connected by means of the concentricenergy-feed systems-E3, El, such as described above, this system beingextended to one side, additional tubes to the number desired being soadded by other concentric lines E5, E6 for example, the last beingconnected to the load. The cathodes of these tubes are connected inseries and to the leads H to which the filament current is fed. Themagnetic field is set up separately for each tube by the aid of thefield coils F.

Another disposition of a plurality of electron discharge systems in asingle envelope is indicated schematically and in perspective in Figure5. Four discharge systems are provided and each of these consists of arectilinear cathode KI and two semi-cylindrical anodes A3, A4. Theelectrode systems are disposed in parallel relation to each other insuch a fashion that their heated cathodes are positioned in one and thesame plane, while the anodes are united to form two corrugated-sheetstructures. This arrangement is placed'within an evacuated envelope andan electro-magnetic coil (not shown) placed around the envelope. Thismethod of mounting results in very simple electrode shapes and supports.The arrangement as shown in Figure 6 is especially suited for a limitednumber of discharge systems, while the scheme shown in Figure 2 isespecially suited for a much larger number.

A particularly simple modification of our invention is made possible bythe use of molded pieces of ceramic body having on their surfacesmetallic coatings or deposits which serve as the anodes. The ceramicbody serves preferably at the same time as the envelope of the tube. As

shown in Figure 7, which is a section transverse to the longitudinalaxis J I and J2 are two bodies of ceramic material disposed one withinthe other and having adjacent surfaces provided with oppositely disposedsemi-cylindrical depressions, the thermionic cathodes K2 lying along theaxis of the resulting tubular chambers. The adjacent surfaces of theceramic bodies are provided with metallic coats or. linings A5 and A6,and these may be made by spattering or spraying, and may serve asanodes. The central bore C may be used for conducting a cooling fluidthru it. An electromagnetic coil (not shown) surrounds the outer ceramicbody. The employment of ceramic material is particularly suitable in thecase of multi unit arrangements inasmuch as it is easy to exactly shapethe material so that the different discharge systems are alike. Theproblem of mounting, which is ordinarily serious in multi unitarrangements is by means of this modification simply solved.

While we have indicated the preferred embodiments of our invention ofwhich we are now aware and have also indicated only one specificapplication for which our invention may be employed, it will be apparentthat our invention is by no means limited to the exact forms illustratedor the use indicated, but that many variations may be made in theparticular structure used and the purpose for whigh it is employedwithout departing from the scope of our invention as set forth in theappended claims.

What we claim as new is:-

1. A magnetically biased electron discharge device including, means forgenerating a magnetic field, a plurality of electron discharge systemspositioned within the magnetic field, each of said discharge systemshaving a straight thermionic cathode and a pair of anodes, the pairs ofanodes of all of the discharge systems being connected together in twogroups the anodes of each group being connected in parallel, saidcathodes and anodes being parallel and coextensive.

2. A magnetically biased electron discharge device including, means forgenerating a magnetic field, a plurality of electron discharge systemspositioned within the magnetic field and including a plurality ofstraight thermionic cathodes mounted parallel toeach other in spacedrelation and coextensive with each other, two sets of anodes cooperatingwith said cathodes, said anodes providing semi-cylindrical surfacesoppositely disposed and coextensive with and surrounding said cathodes.

3. A magnetically biased electron discharge device including, means forgenerating a magnetic field, a plurality of electron discharge systemspositioned within the magnetic field and including a plurality ofstraight thermionic cathodes mounted in spaced relation and coextensivewith each other, two sets of anodes cooperating with said cathodes, oneset of anodes being positioned on one side of said cathodes and theother set of said anodes being positioned on the other side of saidcathodes, each set of anodes being formed of a single sheet of metal andproviding with the other set of anodes oppositely disposedsemi-cylindrical surfaces coextensive with and surrounding saidcathodes.

4. A magnetically biased electron discharge device including, means forgenerating a'magnetic field, a plurality of electron discharge systemspositioned within the magnetic field and including a plurality ofstraight thermionic cathodes mounted in spaced relation and coextensivewith each other, two sets of anodes cooperating with said cathodes, oneset of anodes being positioned on one side of said cathodes and theother set of said anodes being positioned on the other side of saidcathodes, the anodes of each set being electrically'connected together,each set of anodes providing with the other set of anodes op positelydisposed semi-cylindrical surfaces coextensive with and surrounding saidcathodes.

5. A magnetically biased electron discharge device including a pluralityof straight round thermionic cathodes of small diameter mounted inspaced relation parallel and coextensive with each. other, two sets ofanodes cooperating with said cathodes, one set of anodes beingpositioned on one side of said cathodes and the other set of said anodesbeing positioned on the other side of said cathodes, the anodes of eachset being electrically connected in parallel, each set of anodesproviding surfaces oppositely disposed to the surfaces of the other setof anodes to form a chamber coextensive with and surrounding thecathodes, and an electro-magnetic coil surrounding said cathodes andanodes to provide an electro-magnetic field longitudinally of saidcathodes and said anodes.

6. A magnetically biased electron discharge device including means forgenerating a magnetic field, a plurality of electron discharge systemspositioned within the magnetic field and including a plurality ofstraight thermionic cathodes mounted in a circle in spaced relationandcoextensive with each other, two sets of anodes cooperating with saidcathodes, one set of anodes being exterior of said circle of cathodesand providing a plurality of semi-circular surfaces, the other set ofanodes being positioned on the inside of said circle of cathodes andproviding a plurality of semi-circular surfaces oppositely disposed tothe surfaces of said first set of anodes and cooperating with said firstset to substantially surround said cathodes, the exterior set of anodesforming a part of the envelope for said magnetically biased electrondischarge device.

7. A magnetically biased electron discharge device including a pluralityof straight thermionic cathodes mounted in a circle in parallel spacedrelation and coextensive with each other, a plurality of outer anodessurrounding said cathodes and joined to form a portion of the envelopeof the electron discharge device, said anodes pro viding a plurality ofsemi-circular surfaces, a plurality of inner anodes within said cathodesjoined to form an inner wall inside said cathodes and having a pluralityof semi-circular surfaces oppositely disposed and cooperating with thesemicircular surfaces of said outer anodes to provide a tubular chamberaround each of said cathodes, said cathodes being connected in series,and an electro-magnetic coil positioned on and surrounding the outeranodes to provide a magnetic field for said electron discharge device.

'8. A magnetically biased electron discharge device including, means forgenerating a magnetic field, a plurality of electron discharge systemspositioned within the magnetic field and including a plurality ofstraight thermionic cathodes mounted in spaced relation and coextensivewith each other, two sets of anodes cooperating with said cathodes, saidanodes providing semi-cylindrical surfaces oppositely disposed. andcoextensive with and surrounding said cathodes, and concentrictransmission lines connected to said anodes.

9. A magnetically biased electron discharge device including an outertubular insulating member having on its interior surface a plurality ofsemi-circular depressions, an inner tubular insulating member having onits exterior surface a plurality of semi-circular depressions oppositelydisposed and cooperating with the depressions on said outer tubularmember to provide longitudinal tubular chambers} an electricallyconducting coating on the surface of the tubular depressions on each ofsaid insulating members, said conducting coatings providing anodes forsaid electron discharge device, a straight thermionic cathode positionedaxially of each of the tubular chambers, the ends of said insulatingmembers being closed to provide a vacuum tight seal and anelectro-magnetic coil surrounding the outer insulating member to providea magnetic field longitudinally of said cathodes and anodes.

DIE'I'RICH PRINZ. FELIX HERRIGER.

